Power management is one of the most important areas of electronic design. With the proliferation of portable devices and complex, multi-functional integrated circuits, a variety of regulated supply voltages are generally provided to various circuits within a microchip or in a plurality of microchips.
Present CMOS technologies for Low-Dropout Voltage (LDO) regulators of moderate output current (e.g. up to half ampere) dissipate more than a few mA quiescent current at low loading or no loading conditions. Some specialty LDOs of very low power may provide just a few mA's, which may be adequate to power real-time clock and RAM memory circuits. The minimum quiescent current dissipated by a circuit generally relates to a maximum output power requirement of the circuit. Thus, transistors size and their biasing conditions are determined by the size of a series pass transistor and the LDO's overall power handling specification. If bias devices are sized smaller or biased leaner, lower quiescent current may result, but this could heavily compromise the LDO's output power capability and circuit performance characteristics. In the area of portable devices, typical general purpose LDOs may provide 50 mA to over 500 mA.
Thus, it is with respect to these considerations and others that the present invention has been made.